Braun_cathode_ray_tube.jpg
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Summary
Description Braun cathode ray tube.jpg |
English:
Drawing of the first
cathode ray tube
invented by German scientist
Ferdinand Braun
in 1897. It was a
cold cathode
tube, developed from the
Crookes tube
and so did not have a heated
filament
to produce electrons. Instead it produced electrons by ionization of residual gas in the tube with a high voltage. The tube contains a platinum
cathode
electrode
(right end)
, an
anode
electrode consisting of an open tube in the neck to focus the electrons into a narrow beam
(center right)
, a pair of flat
deflection plates
(center left)
, and a paper screen
(left)
painted on the inner side with a fluorescent chemical like zinc sulfide or calcium tungstate. When a high voltage is applied between the cathode and anode, it creates positive ions which are attracted to the negative cathode. When they strike the cathode they knock out electrons (cathode rays) which are accelerated down the tube to the left, through the anode tube, between the deflection plates, and strike the fluorescent screen at the left end, producing a glowing spot. If a second voltage is applied between the deflection plates the electron beam will be repelled by the positive plate and attracted toward the negative plate, so the spot on the end screen will move toward the positive plate.
The small curved side tube attached to the neck (right) is called a "softener". The residual air in the tube, necessary for ionization, tended to be absorbed by the walls over time, making the vacuum "harder", so the tube would eventually stop functioning. The softener tube contained a pellet of chemical that would release gas when heated. If the tube stopped producing cathode rays, a flame would be played over the softener tube, releasing gas to "soften" the vacuum so it would work again. |
Date | |
Source | Retrieved on 11 October 2013 from Eugen Nesper 1921 Handbuch der Drahtlosen Telegraphie und Telephonie , Julius Springer, Berlin, p. 78, fig. 46 on Google Books |
Author | Eugen Nesper |
Licensing
Public domain Public domain false false |
This media file is in the
public domain
in the
United States
. This applies to U.S. works where the copyright has expired, often because its first
publication
occurred prior to January 1, 1929, and if not then due to lack of notice or renewal. See
this page
for further explanation.
|
||
This image might not be in the public domain outside of the United States; this especially applies in the countries and areas that do not apply the
rule of the shorter term
for US works, such as Canada, Mainland China (not Hong Kong or Macao), Germany, Mexico, and Switzerland. The creator and year of publication are essential information and must be provided. See
Wikipedia:Public domain
and
Wikipedia:Copyrights
for more details.
|
Annotations
InfoField
|
This image is annotated: View the annotations at Commons |
931
82
45
60
1084
216
Cathode
992
125
88
39
1084
216
Softener
636
82
130
56
1084
216
Anode cylinder
440
82
178
60
1084
216
Deflection plates
41
23
45
164
1084
216
Fluorescent screen, thin paper screen painted on right side with fluorescent chemical